Advice for building a good Defrag run map

Timers (target_starttimer) are resettable by default.
When using a trigger (trigger_multiple) to activate the timer, use:

The wait key with the value -1 for the trigger or

A patch mesh that blocks the player from reaching the trigger again, to prevent a timer reset.

Use teleporters to slow down the player for gameplay. The initial speed for teleporters is 400 units per second.

Use kill triggers only at the start and later use teleporters for areas a player should not reach (i.e.: lavafield to fall).
If you are at the end of a hard map close to the stop timer, you don't want to get interrupted by a kill trigger or any trigger at all. (see bdfcomp50-3 or run_undead_aurum_rastman)
There are maps including a kill trigger on purpose since some tricks can only be done with a certain speed.. (see czsk-2k5_MegA-TecK)

Don't remove shortcuts if you find them, this is part of DeFRaG.
Don't release a second version of your map.

Adjust the graphics for the gameplay, therefore test the gameplay before doing the graphics.
Keep in mind players use first person view.

Do not use baseq3 or modification textures because the map will be unplayable in other mods or games (idtech3 compatible engines) due to missing textures.

Add many well placed checkpoints.

Try not to create invisible (player) clips. They destroy the gameplay.
On the other hand clip small holes, excessive solid map models and if necessary (nonsolid) grates or glass.

Some gameplay killers such as fog that blocks the view, annoying sounds, especially at the start, flashing light and no markers for the start and stop timer.

Bear in mind that players will use or do anything to start the timer with more speed. (see 01.)

The difficulty level can be the main factor for a good map. Is it to easy or to hard then you lose the interest fast. Possible targets can be newbie, average or advanced players.
In case it is for yourself make the map a little bit harder in terms of the difficulty level. The more you play the map the easier it gets.

You should know there is no extra instance for each player in defrag, therefore doors and buttons can be activated by each player in multiplayer.
(See the maps runackman, dfcomp003 or cellar2)